River VL 4 Flashcards
Definition: Hyporheic interstitial
The hyporheic interstitial (also known as hyporheal zone) is the area of small spaces between sand and gravel under and next to a river or stream. Water from the river mixes with groundwater in this zone, creating a special habitat for certain small animals and plants, and helps clean and recycle nutrients in the water.
Definition: Exfiltration and Infiltration
Exfiltration:
* Specifically refers to the movement of water out of river channels into the surrounding soil or groundwater.
* This process can carry nutrients, dissolved oxygen, and other substances from the river into the hyporheic zone or groundwater.
Infiltration:
* Refers to the broader process of water entering the soil from the surface.
* This process can occur anywhere water is present on the surface, such as from rainfall, irrigation, or river overflow, and is not limited to areas near rivers and streams.
* It can increase the groundwater level and therefore support rivers, as the water pressure from beneath the hyporheic interstitial pushes into the river bed.
What is another name for primary consumers in river ecosystems? Name three different primary consumer groups!
Primary consumers in river ecosystems are considered zooplankton.
1. Crustaceans (Krill)
2. Rotifers
3. Ciliates (they have hair-like structures called cilia for movement)
How is the relation between percolation rate (Versickerungsrate) und respiration?
The percolation rate can influence the availability of oxygen in the environment, which in turn affects the respiratory
processes of organisms living in that environment.
-> Respiration (partly) depends on percolation rate.
What is the normal oxygen saturation at 20°C? What happens to the oxygen saturation at lower temperatures?
At 20°C, the oxygen saturation is normal at about 8 mg/L
At lower temperatures, the oxygen saturation is generally higher.
Describe briefly the process of denitrification
Denitrification is a microbial process in which specialized bacteria convert nitrate (NO3-) and nitrite (NO2-) into nitrogen
gas (N2) or nitrous oxide (N2O) under anaerobic (oxygen-deprived) conditions.
What is the zone adjacent to a river called?
What is the difference to the Hyporheic interstitial?
Parafluvial
- While the parafluvial zone refers to the area directly beside the river, whereas the hyporheic zone is beneath and alongside the river.
**Water in groine fields is often completely ______ (word for illuminated). Water in the main stem is rather _____ (word for dark).
Water in groine fields (shallow) is often completely euphotic.
Water in the main stem (deep) is rather aphotic.
The euphotic zone is the upper layer of the water column where photosynthesis occurs, supporting primary production and a diverse array of marine life.
In contrast, the aphotic zone is the deeper, dark layer of the water column where light is absent or minimal, and primary production relies on alternative energy sources
What is the consequence of wastewater inflow in rivers?
Input of organic load -> Input of nutrients
Results in phytoplankton growth -> oxygen decrease due to respiration
Why is the chlorophyll content in groine fields low in late spring and higher in summer?
Low in late spring due to grazing from zooplankton
Higher in summer due to increased temperatures and better light conditions
Is there a low or high habitat diversity in groine fields?
LOW habitat diversity
